Most high-speed printers presently in use employ ink as the printing means. Since the use of inked ribbons has substantial drawbacks, the process of applying liquid ink directly at the interface between the printing device and the print media has become more common. This method preferably uses an ink reservoir with a substantial capacity so as to extend the interval between either the replacement of the ink supply container or the refilling of the reservoir. In such ribbonless print mechanisms, ink is delivered from the reservoir to print wires through a "wick" which utilizes the principles of capillary action. Devices utilizing such ink reservoirs are shown in U.S. Pat. No. 4,353,654 and U.S. Pat. No. 4,400,102, both of which are assigned to the assignee of the present invention.
The reservoir is typically mechanically attached to the print mechanism and therefore any movement of the underlying carriage causes the ink to slosh within the reservoir resulting in leakage through any vent(s) that may be present. The movement principally responsible for causing the sloshing of the ink is the reciprocating movement of the carriage which occurs while the apparatus is printing. The movement also causes bubbles to form at the surface of the ink, and with the movement accompanying the printing mechanism, bubbles foam up through reservoir vent(s), particularly when there is a substantial amount of ink still in the reservoir. Elimination of the vents will not solve the problem because the vents are necessary for the proper flow of ink from the reservoir to the printing device. The resulting loss of ink also impedes removal of the reservoir because with ink covering the reservoir, it is difficult to securely grasp the reservoir. As a result, refilling or replacing the ink supply becomes a messy and time-consuming operation.
The prior art has attempted to deal with the ink sloshing problems by employing baffles within the ink reservoir to minimize the loss of both liquid and foaming ink. These baffles attempt to minimize the movement of the ink within the reservoir. By minimizing the ink's movement it is hoped that less sloshing and foaming of the ink will occur. These baffles, however, have not proven to be 100% effective in preventing sloshing or foaming of the ink and loss of ink still occurs. Additionally, this problem has been addressed by not completely filling the ink reservoir, but this fails to make maximum use of the container volume thereby necessitating more frequent replacement or refilling.
A principal object of the present invention is to permit a liquid ink mechanism to be used in conjunction with a reciprocating printer mechanism without loss of liquid or foaming ink through a vent hole.
Another object of the present invention is to permit the ink reservior to be filled to its maximum level without loss of ink due to reciprocating motion of the printing mechanism thereby permitting maximum intervals to elapse between refills.
A further object of the present invention is to keep the ink reservoir clean for ease of handling during reloading and refilling operations.